nice library. It provides just whats needed to solve expressions that were keyed in by users in a secure manner (ie without opening code injection possibilities). Its also way faster than neccesary for that use case.

One caveat is its verboseness when it fails to parse a expression: MEE will die() here and one must catch this with eval{}. In my case this still gives a lot of trace output through stderr which will then clutter the logs... Its best to write code that produces valid (parsable) expressions all the time. In cases where this can't be done or is difficult to do (such as mine) it would be good to have a (silent) way to test validity of an expression before solving it. I don't know how feasible that thought is however.